Application of open‐source photogrammetric software MicMac for monitoring surface deformation in laboratory models

Abstract

Quantifying deformation is essential in modern laboratory models of geological systems. This paper presents a new laboratory monitoring method through the implementation of the open‐source software MicMac, which efficiently implements photogrammetry in Structure‐from‐Motion algorithms. Critical evaluation is provided using results from two example laboratory geodesy scenarios: magma emplacement and strike‐slip faulting. MicMac automatically processes images from synchronized cameras to compute time series of digital elevation models (DEMs) and orthorectified images of model surfaces. MicMac also implements digital image correlation to produce high‐resolution displacements maps. The resolution of DEMs and displacement maps corresponds to the pixel size of the processed images. Using 24 MP cameras, the precision of DEMs and displacements is ~0.05 mm on a 40 × 40 cm surface. Processing displacement maps with Matlab® scripts allows automatic fracture mapping on the monitored surfaces. MicMac also offers the possibility to integrate 3‐D models of excavated structures with the corresponding surface deformation data. The high resolution and high precision of MicMac results and the ability to generate virtual 3‐D models of complex structures make it a very promising tool for quantitative monitoring in laboratory models of geological systems.

Mechanisms of overburden deformation associated with the emplacement of the Tulipan sill, mid-Norwegian margin

“…These experiments show that when a dome associated with an intruding saucer-shaped sill exhibits a plateau shape, like that of the Tulipan dome, the largest convex curvature of the paleo-surface occurs near the upper, monoclinal hinges of the dome (see Figure 1). Thus, the resulting fractures are concentric, parallel, and close to the dome edge (see also Galland et al, 2016). The close relation between these tensile fractures and the hydrothermal vent complexes (Figures 7a and 8a) suggests that the former might have channeled the over-pressurized fluids, and so controlled partly the locations of the vents.…”

“…When the stresses generated in response to elastic bending exceed the strength of the overburden rocks, failure occurs and characteristic fracture patterns develop. These fracture pattern can be classified into four main types depending on their location in the overburden (Figure 1b): (1) circumferential, tensile fractures at the surface coincident with the area of the largest convex SK24 Interpretation / August 2017 curvature above the sill edges (e.g., Pollard and Johnson, 1973;Bunger and Cruden, 2011;Galland et al, 2016), (2) radial tensile fractures (mode I) and/or normal faults (mode II) due to an extensional regime (i.e., outer-arc stretching) in the central part of the dome structure Magee et al, 2013;Galland et al, 2016), (3) dilational fractures near the peripheral hinge of the dome, close to the intrusion tips, which progress toward the surface (Pollard and Johnson, 1973;Menand, 2008;Thomson and Schofield, 2008;Galland and Scheibert, 2013;Agirrezabala, 2015), and (4) shear fractures resulting from differential uplift at the dome edge (de Saint-Blanquat et al, 2006;Hansen and Cartwright, 2006;Wilson et al, 2016).…”

“…The intrusion hosting sedimentary infill is composed of mainly claystone, with interbedded sand- The simple elastic model envisages the formation of a dome structure (forced fold) above an intrusion (e.g., Pollard and Johnson, 1973;Galland and Scheibert, 2013). (b) Four fracture types related to elastic overburden deformation: (1) circumferential, tensile fractures coincident with the area of the largest convex curvature of the dome (e.g., Pollard and Johnson, 1973;Bunger and Cruden, 2011;Galland et al, 2016), (2) radial tensile fractures (mode I) and/or normal faults (mode II) due to outer-arc stretching (Hansen and Magee et al, 2013;Galland et al, 2016), (3) dilational fractures progressing toward the surface (Pollard and Johnson, 1973;Menand, 2008;Thomson and Schofield, 2008;Galland and Scheibert, 2013;Agirrezabala, 2015), and (4) shear fractures resulting from differential uplift (de Saint-Blanquat et al, 2006;Hansen and Cartwright, 2006;Wilson et al, 2016). (c) Model of volume reduction, i.e., porosity decrease, affected by the aureole of the intrusion (e.g., Hansen and Cartwright, 2006;Jackson et al, 2013).…”

Displacement Monitoring of the Slope at Tunnel Face Based on PhotoModeler Scanner System

“…At present, we mainly set up displacement monitoring points on the slope, then monitoring the displacement of these points through leveling and total station instruments. With the development of the monitoring technology, the use of close-range photogrammetric equipment and laser scanner to monitor the displacement is also increasing in recent years, and using them could get richer data (Galland et al, 2016; Barbarella et al, 2013). In terms of economy and convenience, laser scanners and high-precision total stations' prices are high.…”

Terrain changes from images acquired on opportunistic flights by SfM photogrammetry

“…1) produces a georeferenced DEM and orthoimage from input imagery and geolocation data (Snavely et al, 2008;Niethammer et al, 2010;Westoby et al, 2012;Kääb et al, 2014;James and Robson, 2014;Ouédraogo et al, 2014;Tonkin et al, 2015;Nolan et al, 2015;Galland et al, 2016;Eltner et al, 2016). Typically, the camera's intrinsic parameters (sensor and optics) are determined first, along with the relative camera locations and pointing angles from the photogrammetry itself.…”